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From: dennisg@fritz.UUCP
Newsgroups: sci.electronics
Subject: Re: Infra-Red Receiver?
Message-ID: <4095@fritz.felix.UUCP>
Date: Fri, 3-Apr-87 20:54:56 EST
Article-I.D.: fritz.4095
Posted: Fri Apr  3 20:54:56 1987
Date-Received: Sun, 5-Apr-87 09:44:50 EST
References: <1922@ihlpl.ATT.COM> <100500005@datacube>
Reply-To: dennisg@fritz.UUCP (Dennis Griesser)
Organization: FileNet Corp., Costa Mesa, CA
Lines: 13

In article <100500005@datacube> dje@datacube.UUCP writes:
>I generally mistrust  LED markings;  a disease  I picked  up from too
>many Poly-Packs (remember them?)  purchases.   To  check polarity and
>operation at the same time, I use a 330 Ohm resistor in series hooked
>to a 5V supply (20 Ma).  Proper polarity is indicated by the LED on.

Except that the LED in question was IR.  Even when I got it connected 
properly, there was no emission that I could see.

But I wasn't asking about how to find the correct polarity.  No problem
there.  I was merely lamenting the fact that a large company like
Radio Shack can sell thousands of IR LEDs (with backwards data sheets)
to unsuspecting customers.